(a) Field of the Invention
The present invention relates to an electrostatic ink jet recording device having a stirring system for circulating the ink in an ink reservoir by bypassing an ink chamber.
(b) Description of the Related Art
Electrostatic ink jet recording devices have been proposed comprising a stirring mechanism for an ink chamber to maintain the density or concentration of toner particles in pigmented ink at a constant across the ink chamber of the ink jet recording head.
Patent Publication No. JP-A-4(1992)-216940 proposes a stirring mechanism implemented by a ultrasonic actuator, which is disposed on the outer wall of the ink jet recording head. The ultrasonic actuator generates ultrasonic wave in the ink chamber to dissolve and distribute agglomerated pigment in the ink in the ink jet recording head.
Patent Publication No. JP-A-60(1985)-110458 proposes another stirring mechanism, which is disposed in a second chamber of an ink reservoir of the ink jet recording head. The stirring mechanism comprises a rotating blade member for generating a stirring flow of the ink in the second chamber.
Patent Publication No. JP-A-61(1986)-227059 proposes another stirring mechanism implemented by a combination of a jet nozzle and an uneven surface of the inner wall of the ink chamber, or pump , screw or a vibrator for stirring the ink in the ink chamber.
Those proposed ink stirring mechanisms are effective to provide a uniform concentration of the toner particles in the ink to some extent for an excellent image quality. However, those mechanisms have respective problems such as high costs, complicated configurations, or reliability of the mechanism.